Device for producing typewritten master sheets



April v5, 1949. c. A. BERGSTEN DEVICE FOR PRQDUCING TYPBWRITTEN MASTER SHEETS 6 Sheets-Shevet 1 Filed lay 19, 1945 Ap 5, 1949. c. A. BERGSTEN DEVICE FOR PRODUCING TYPEWBITTEN ASTER SHEETS Filed my 19, 1945 6 Sheets-Sheet 2 L .m w k n. N ,my Y vm. NQ. n 7 w hm, Nn NNN mmm. J mm l -l w N4 17. j n N94 mm. fr?. mi I n mi ley 1 l, @NNW r Q m NWW ,M Nm xiii, www vwd /lw IL. IHHI.. IN| .|.|||I.. I I l l I Il Il I v IIL?. l t Sw. Y-.. L NM2] -mm m wwlw u --1 Hummm.- 14H1 l Dm SN I l1 lllliif|imhl v.. hm mw ||d||, l l IL vl mw. l lldr-IL v QN EF 5:... uw. nh @WN $1 3N A $4 Q W .KIN H T.

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DEVICE Fon PRODUCING TYPEWRITTEN MASTER SHEETS Filed May 19, 1945 c. A. BERGsTl-:N

6 Sheets-Sheet 6 Patented Apr. 5, 1949 DEVICE FOR PRODUCING TYPEWRITTEN MASTER SHEETS Charles A. Bergsten, Evanston, lll., asslgnor to Ditto, Incorporated, Chicago, Ill., a corporatie of West Virginia.

Application May 19, 1945, Serial No. 594,733

13 claims. l

The present invention relates to an attachment for all writing or imprinting machines that is particularly adapted to produce reverse or mirror script masters for use in the duplicating systems whereby a master sheet having the material to be reproduced typed thereon in copyable ink is brought into contact with a. copy sheet, and sufcient moisture, to dissolve a small amount of the ink from the master sheet to thus produce a copy. Certain advantages of my invention are not limited to this type of operation, but my invention exhibits its greatest advantages in the making of master sheets for use in the duplicating operation just referred to.

It is the principal purpose of my invention to provide means whereby the master sheet can be passed through the writing or imprinting operation and given the necessary mirror script copy on the back in hectograph carbon without danger of any smudging of the hands and clothing of the operator or of the master sheet. The importance of this cleanliness from smudging will be readily apparent to those who understand how easy it is to get smudges from handling sheets of carbon. The smudges are very objectionable from the standpoint of the operator because it takes time for cleaning up after inserting the carbon. They are also very detrimental from the standpoint of copies because any smudge on the master sheet will be reproduced in the same manner as the mirror script will be reproduced. According to my invention I combine with the platen of the writing or imprinting machine a strip of carbon and means for mounting the carbon so that the operators hand need not touch the carbon strip itself, either on the coated or uncoated side, at any time. Likewise, I so arrange the feeding of the master sheet itself with respect to the platen that the master sheet and carbon sheet interengage only at the point of contact by the type, and one can slide relative to the other without smudging the master sheet with the carbon.

It is a further purpose of my invention to provide a device of this character with means whereby the entire surface of the carbon strip can be utilized even though only a small portion of the master sheets brought in contact therewith have any matter typed thereon.

It is also a purpose of my invention to provide a novel means for maintaining the master sheets feci through the machine free of streaks or smudges from the carbon due to-one of them being moved with respect to the other.

My invention contemplates also the provision of a novel arrangement of parts whereby used carbon may be stored during the operation of typing the masters and disposed of at intervals without any danger of soiling the hands or clothing of the operator.

The nature and advantages of my invention will appear more fully from the following description and the accompanying drawings wherein a preferred form of the invention is shown. It should be understood however that the drawings and description are illustrative only and should not be taken as limiting the invention except insofar as it is limited by the claims.

In the drawings:

Figure 1 is a view in side elevation of a writing machine embodying my invention;

Figure 2 is a fragmentary view partly in section illustrating more in detail part of the mechanism shown in Figure 1;

Figure 3 is a fragmentary sectional view taken substantially on the line 3-3 of Figure 4;

Figure 4 is a plan view illustrating one embodiment of the invention;

Figure 5 is a front view of the device;

Figure 6 is a sectional view taken on the line 6--6 of Figure 1;

Figure 7 is a sectional view taken on the line 'l--l of Figure 5;

Figure 8 is a fragmentary perspective view illustrating a part of the mechanism shown in the Figure 7;

Figure 9 is a fragmentary sectional view taken substantially on the line 9-9 of Figure 7;

Figure 10 is a sectional view similar to Figure 7 but illustrating a slightly modified form of the invention wherein the carbon strip is Wound from one spindle to another; and

Figure 11 is a fragmentary end view of the form of the invention shown in Figure 10, showing the interconnecting drive mechanism from the take-off spindle to the take-up spindle for the carbon strip.

In the present invention means are provided whereby a master sheet or strip I0 is adapted to receive on one side thereof a type imprint, while on the opposite side thereof a deposit of hectograph carbon from a supply strip Il is made in the form of a reverse image of the typed message. In the making of master sheets of this type it is often the case that the area occupied by the material supplied is very small in comparison with the total area of the sheet. When such master sheets are made by using a carbon sheet for each master sheet the process is quite wasteful of the material and it necessitates the handling of a large number of sheets coated with carbon which tend to smudge quite easily. This is objectionable from the operators standpoint, and the possibility of getting smudge spots on the masters making them unserviceable is also a handicap.

It has heretofore been 'proposed in many cases to utilize carbon in the form of continuous strips' for the making of copies. Continuous strip forms have been made and are available for use at present wherein the transfer medium or carbon is combined directly with the form of record sheet. Such forms require the use of as much carbon as master sheet and it necessitates the separation of the carbon from the master. There are many so-called snap-out forms developed to attempt to cure the difficulty of handling the carbon and the record sheet. According to my invention' the necessity for using so much carbon or transfer` consists essentially of two brackets I2 and IE!` that are constructed to be mounted upon fixed parts of the machine. In the kind of machine to which the brackets are attached as shown herein, there is a cross bar I4 mounted on two rearwardly extending lugs I5 and I6 of the machine frame. The brackets I2 and I3 have bifurcated end portions I1 and |8 that t over the cross bar I4 just inside the lugs I5 and I6. The illustrated machine is a typewriter that has a rectangular cross bar I9 between its two side frames 20 and 2|. The brackets I2 and I3 are provided with notched extensions 22 and 23 respectively so that the brackets may rest upon the cross bar I9.

The brackets I2 and i3 serve as the supporting means for two side frames 24 and 25. These side frames are extended forwardly over the platen roller 26 of the typewriter so that the mechanism carried by the side frames is positioned to cooperate with the platen roller and the operating.

mechanism of the typewriter or other machine to which the platen roller is attached. In the form of the invention shown in Figures 1 to 9 inclusive the side frames 24 and 25 are adapted to support the carbon strip I I with one end of the strip wound about a spindle 21 and with the other end of it inserted in a removable disposal container 28. The path of the carbon strip from the spindle 21 to the disposal container 2B is shown best in Figure '7 of the drawings. The carbon strip extends downwardly around the platen roller 26, and then upwardly and beneath a spring pressed idler roller 29 into an elongated guide passage 30 which is made up of two spaced plates 3| and 32. The plate 3| is fixed to the side frames 24 and 25, but the plate 32 is removably mounted. The upper en d of the plate 32 is hung upon two pins 33 and 34 (see Figure 9) by means of clips 35 and 36. Part-way down the guide 32 from the clips 35 and 36 the side frames 24 and 25 have lugs 31 and 38 struck inwardly so that the guide 32 can lie against the lugs. The guide is cut out as indicated at 39, 4U, 4| and 42 to permit the lugs 31 and 38 and the pins 33 and 34 to pass through the guide when it is necessary to move the guide for any purpose.

At the upper end of the passage 30 the carbon sheet is directed over a bar 43 and a plate 44, both of which are mounted inthe side frames 24 and 25. It will be noted that the plate 3| is bevelled at its ends and extends into .engagement with the bar 43 -and into close proxirnityto the vroller 29, that the plates 3| and 32 are curved at |65 and |66 to provide a gradually curving entrance to the passage 30 and that the plate 32 has a curved lip |61 at its upper end directing the strip II toward the bar 43 and the plate 44. The bar 43 has a groove 45 therein and a cutter blade 46 is adapted to cooperate with this groove in cutting off the carbon strip when the disposal container 28 is to be emptied and there is still carbon being fed from the spindle 21. The cutter 46` is a rotary one being rotatably mounted on a frame 41 that slides lengthwise between the side frames 24 and 25 on a rectangular guide bar 48. A hand lever 49 projects upwardly from the frame 41 for moving the cutter into cooperative relation to the groove and lengthwise thereof to cut off the strip The receptacle 28 as shown best by Figures 5, '7 and 8 is mounted for ready removal so that the carbon wound therein can be easily disposed of by holding the receptacle 28 over a waste basket and emptying the receptacle. The means for removably mounting the receptacle 28 comprises grooves `28a in the opposite ends of the receptacle and inwardly projecting elongated posts 282) and 23o fixed upon the side frames 24 and 25. The receptacle 28 is so mounted that it can be removed without diiculty, merely by grasping it in the middle and lifting it upwardly and outwardly. Thus it is entirely unnecessary for the carbon to be engaged by the hand of the operator and the receptacle 28 can be washed or cleaned in any way desired.

The platen roller 26 does not feed the master sheet l0 like the ordinary platen roller feeds paper in a typewriter or similar machine. The side frames 24 and 25 carry suitable mechanism whereby the sheets I0 or a web of master sheet 'material can be advanced without becoming' smeared by the carbon strip I. An examination of Figure 7 will illustrate the path of the master sheet I0. The machine illustrated, to which the invention is applied, carries a guide plate 59 that is adapted to direct a sheet into engagement with the platen roller 26 inthe ordinary use of the typewriter. The typewriter shown, and similar machines usually carry pressure rollers 5I and 52 which are adapted to press the sheets against the platen roller 26. These pressure rollers however, can'be moved and held out of the way of the path of the sheets guided by the plate 50, in machines of this character, and in accordance with my invention they are not utilized to press the master sheet against the platen roller. The guide 50 in such machines is spaced sufficiently from the roller 26 to allow free movementof a sheet ID without ybinding the sheet, whenits forward edge is led upwardly to a sheet advancing means forming part of this invention, that vis carried bythe side framesv 24 and 25.

The sheet advancing means above referred to comprisesv two spaced shafts 53 and 54. The shaft 54 is a drive shaft and is journalled in the side frames 24 and 25, there being reduced portions 55 and 56 at the opposite ends of the shaft 54 (see Figure 6). The shaft 53 also has its opposite ends reduced in size as shown at 51 and 58, and these reduced end portions are slidably mounted in slots 59 and 60 that are provided in 5. the slde frames 24 andY 25. The shaft .S4-has two separate rollers 6| and 52 slidably but non-rotatably mounted thereon. Each of these rollers comprises a core portion 63 and a soft rubber rim portion 64. The core portion 53 has a flattened face 63a. (see Figure 7) in the bore therethrough to ride on a attened side 95 of the shaft 54 so as to insure rotation of the rollers and 62 with the shaft. The shaft 54 is rotatable by means of a handwheel 66 at one end and at the other end it has a ratchet wheel 61 fixed thereon. The reduced end portion 55 of the shaft has a attened surface 60, and the ratchet wheel 61 has a dat face in the bore thereof to engage the surface 68. A washer 59 and a nut 10 engaging the reduced threaded end 55' of the shaft 54 serves to secure the ratchet wheel 61 in'place. The reduced portion 55 also mounts a pawl shield 1|, the function of which Will be described more fully hereinafter. A wear plate 12 is mounted between the shield 1l and the enlarged portion of the shaft 54. The shaft 53 has two smaller rollers 13 and 14 slidably and rotatably mounted thereon. These rollers 13 and 14 are coupled to the rollers 5| and 52 by means of combination paper guides and coupling members 15 and 15.

The members 15 and 15 have bifurcated end portions 11 and 18 that engage in corresponding annular grooves 19 and 80 provided in the rollers 13 and 14. The members 15 and 1B are pivoted upon reduced end portions of the hubs G35-and are held in place by rings 8| and 82 which fit over the reduced end portions of the hubs 63. Ihe rings are held in place by two set screws 83 and 94. Said members 15 and 16 have guide anges 85 and 85 at the lower ends thereof.

In order that a sheet may be released after it is once gripped between the rollers 6| and 52 and the rollers 13 and 14, the shaft 53 is movable in the slots 59 and 60 away from the shaft 5S. Normally the shaft 53 is urged toward the shaft 54 by two lever arms 81 and 38. The lever arms 81 and 89 are mounted upon a cross bar 89 that extends between the side frames 24 and 25. They have upwardly extending portions 90 and 9|l which are connected by springs 92 and 93 to posts 94 and 95 that are secured in the side frames 24 and 25. A yoke member 96 has depending legs the end portions of which, 91 and 98 engage the opposite side ofthe shaft 53 from the arms 81 and |38. Normally the yoke member 96 is held away from the shaft 53 by means of a spring 99 that extends from said yoke back to a post |00 that is mounted in the side frame 24. The yoke however, can be latched in position to push the shaft 53 away from the shaft 54 by a'latch member |0| that is pivoted at |02 on a post carried by the side frame 24. The latch is urged downwardly by a spring |03 that is also secured to the post |00. The latch is provided with a shoulder at |04 to engage an edge of the yoke 95.

Upon reference to Figure 7, it will be evident that by the mechanism described master sheets I0 can be drawn about the platen roller by means of the rollers 6| and 92 in cooperation with the rollers 13 and 14 and that this movement is independent of the movement of the surface of the platen roller that ordinarily serves this purpose in a machine such as that to which the invention is applied. The advantages of having the master or record sheet moving means move the sheet independently of the surface of the platen .roller will be brought out more fully hereinafter in connection with means whereby it is possible to prevent the carbon sheet from engaging a 6 record sheet at all or to enable the carbon sheet to engage a master sheet only at the point where typing is being done.

It is desirable to have the roller 29 yieldingly mounted so that it can be lifted away from the platen roller 26 for purposes of getting the carbon started into the channel 30. I, therefore, mount the roller 29 upon two lever arms |05 and |00 that are pivoted upon a cross bar |01 connecting the side frames 24 and 25, sald'arms being spaced from the side frames by means of the tubular bosses |50 and IBI and said bar |01 having reduced threaded ends |62 with which nuts |63 engage to secure the bar |01 in position. The lever arms |05 and |06 have rearward extensions |08 and |09 respectively and springs i|0 and are connected from the lever arms |08 and |09 to pins ||2 and I3 (see Figure 5) that are mounted on the side frames 24 and 25. The springs ||0 and yieldingly urge the roller 29 into engagement with the platen roller 26 at all times. However, it is a simple matter to lift the roller 29, if it is desired to enable one to pass the entering edge of a carbon strip between it and the platen roller.

One of the diiculties in attachments of this character that have heretofore been proposed is the difficulty of avoiding smudging of the master sheet as it passes over the carbon sheet where one sheet is moved at a different rate than the other. My invention provides means whereby this may be avoided and a sheet, with or without additional copy sheets can be fed' through the machine and protected from smudge by engagement with the carbon sheet at the will of the operator. In other words, the operator can utilize the carbon strip for making reverse mirror script legends on the back face of thev sheet corresponding to the 'type shown on the front face thereof, or he can, if desired, entirely prevent the carbon strip from engaging the record sheet material being moved through the machine. This feature of the invention is highly important because in so many cases the machine to which this attachment is applied must also be used for ordinary correspondence. The attachment does not prevent the machine from being used for that purpose and it makes it possible to make both a record carbon and a duplicating carbon in mirror script at the same time that an original piece of correspondence is written. The means that enable me to accomplish these various results comprises the combination with the carbon strip handling means and the added record or master sheet feeding means of the platen roller and a separating shielding member H4.

|Ihe shielding member ||4 is of flexible sheet material. Examples of material that can be used for this member are ordinary paper sheets, cloth sheets, vellum sheets and synthetic resin sheets. The material should be tough and capable of withstanding hard usage because at certain times it is being pounded by the typewriter keys and at vall times it is being subjected to engagement by the paper sheets that are fed through the machine. The shield l I4 is looped through a slot l I5 that is provided in one edge of a channel shaped clipl I6. The material of the'shield ||4 is folded over and either fastened by stapling or allowed to hang from the fold, depending upon whether or not fastening is necessary. It will be noted from Figures 6 and 7 of the drawings that the clip ||6 is adapted to hook over the cross bar |01. The clip is so constructed that it has two positions on the bar |01. The two outwardly bowed portions I |'I and I I8 nearest the edge that mounts the shield ||4 provide one position while the base portion I9 of the clip provides the other position. These positions are sufficiently far apart that when the portions ||1 and ||8 are in engagement with the cross bar |01 the end of the shield ||4 is below the point X Where the type engages the sheet lo.

To illustrate the exact position I have shown a type carrying lever |20 substantially in impressing position in Figure 7. When the type strikes the sheet I as shown in Figure 7, the sheet will be engaged with the carbon and receive a reverse imprint on the back. However, if the clip ||6 is shoved down so that the part IIS thereof engages the bar |01, it will allow the shield I |4 to extend farther around the platen roller 26 into position to block engagement of the sheet with the carbon strip beneath the type.v In such a case the back of the sheet will receive no imprint from the carbon strip II. It is thus possible for me to use the carbon strip or not use the carbon strip as desired. It is also possible to make ordinary carbon copies of correspondence by inserting a record sheet, a transfer carbon and a second sheet between the guide 50 and the shield ||4, and the second sheet may or not have the reverse or duplicating message applied thereto depending upon the position of the shield ||4 Mention heretofore has been made ofthe manner in which the paper feed rollers 6| and 62 are driven by means of the ratchet Wheel 61. The platen vroller 26 is normally driven by a ratchet and pawl arrangement that can be adjusted to give longer or shorter strokes. This known construction is utilized in connection with my invention to establish drive means for the shaft 54 to the ratchet wheel 61. The particular mechanism is shown best in Figures 1 to 5 inclusive. The typewriter is provided with the usual carriage lever |22. This leveis pivoted at |23 on the frame of the typewriter and has an arm |24 that is connected to a link |25 that is adapted to operate the shaft 54 through a mechanism to be presently described. Another link |26, also connected to the arm |24, is adapted to rotate the platen roller 26 in the particular machine illustrated. The link |26 connects to a pawl arm |21 that is pivoted on the platen roller shaft |28. This pawl lever carries a pawl |29 that is adapted to engage a ratchet wheel |30 fixed to the platen roller. The pawl is held away from the ratchet wheel |30 by means of a shield |3| that can vbe shifted by a hand lever |32 so as to expose more or less of the teeth of the ratchet wheel to the pawl during a complete stroke thereof as effected by the lever |22. This mechanism or its equivalent is common in typewriters.

The mechanism by which I operate the ratchet wheel 61 on the shaft'54 includes the link |25. This link extends rearwardly andis supported at its rear end by an arm |33 that is pivoted on the side frame 25 at |34. The arm |33 also car ries a second link |35 which is pivoted on the same pin |36 that pivots the arm |33 to the link |25. 'Ihe link |35 connects toa pawl lever |31 that is mounted on the reduced portion 55 of the have the engagement effected and the period of engagement is controlled by adjusting the shield 1|. This adjustment is accomplished by providing on the frame a series of notches |4|, and providing on the shield 1| aspring pressed plunger |42 for engagement in the notches |4I, the position of which is adjusted by means of the lever |64. The ratchet wheel 61 has a spring pressed roller |43 (see Figures 1 and 6) engaging it. This roller is carried by a lever |44 that is pivoted on a screw stud |45 on the side frame 25. A spring |46 urges the lever in such a direction as to pressv the roller |43 against the teethof the ratchet wheel. y 4

In normal operation of the machine for making master copies for duplicating purposes the carbon stripII is moved entirely by the platen roller 26. `The shield |3| is therefore, so set that for each actuation vof the lever |22 the platen roller will be advanced only one step. 'I'his means that all of the available space on the carbon strip will be utilized. The shield 1I however, maybe set for double or triple space with the shield |3| set as abovestated so that for actuation of the lever |22-the master sheet will be advanced far` ther than the carbon strip. When it is desired to move the master sheet through a large dis-Y tance, this is accomplished by the hand wheel 66 without any movement whatsoever of the carbon strip. The guiding of the master sheet by means of the members 15 and 16 and the guide 50 is such that it is possible to reverse the movement of the paper by operation of the hand wheel 66 because there is very little friction upon the paper due to these guides. Furthermore, the shield ||4 is of such a nature that it does not present any serious friction to the movement of the paper.

Referring now to Figures 10 and 11 there is shown a slight modification of the device wherein a second spindle 21a. exactly like the spindle 21 is used to wind up the'carbon'strip after it is utilized. The mounting of the two spindles is the same and the description of one mounting is believed to be suiicient for the purposes of this application.r Figure 4 of the drawings shows that the spindle is held between two stub shafts |41 and |48 that are journalled in the side frames 24 and 25. The shaft |41 is slidable to permit- 'release of the spindle 21 and the shaft has a head against a flattened portion |50 of a member that shaft 54 between the ratchet wheel 61 and the side frame 25. A spring pressed pawl |38 is carried by an extended portion |39 of the lever |31. A spring |40 normally urges the pawl |38 toward the ratchet wheel 61. However, the shield 1| is positioned to prevent the pawl |38 from engaging the ratchet Wheel except when it is desired to is fastened in each end of the spindle. The head portion on the stub shaft |48 is shaped the same way so that spindles are reversible in the machine without any difficulty. A spring |5| urges the shaft |41 into a position to hold the spindle in engagement with the shafts 41 and |48.

In the main form of the invention the spindle shafts |41 and |48 both have knurled knobs |52 and |53 thereon. However, in the modified form of the invention where the additional spindle 21a is mounted I provide the shaft |48 corresponding to the shaft |48 in said main form with a lpulley |54 and I provide the shaft |55 of the 4. The combination with a writing machine or imprinting apparatus having a roller platen,

the carbon strip in either loading or unloading the attachment. This is accomplished by providing the carbon strip with long leaders of White paper or equivalent at its opposite ends. The length of the leader should be such as to extend from the spindle 21 around the platen onto the spindle 21a far enough to secure it so that the advance of the strip would thereafter be assured without the necessity of the operator handling the carbon strip itself. Likewise in the form of the invention shown in Figure 7 the end strip which is free of carbon must be of such length as to extend from the spindle r2'! around the platen roller through the channel 3U and over the bar :i3 into the receptacle 28. This length of leader protects the roller in handling and shipping and protects the operator in loading and unloading the apparatus. Smearing of the sheets l0 is prevented by the shield H4. The shield is easily replaced and if at any time it becomes damaged, a new shield can be inserted without difculty.

From the foregoing description it is believed that the nature and advantages of my invention will be apparent to those skilled in the art.

Having thus described my invention, I claim:

1. The combination with a writing machine or imprinting apparatus'having a platen, of means for producing master sheets thereon, comprising means disposed behind said platen and extending forwardly and beneath the same for guiding sheet material across said platen, means for feeding a carbon strip across said platen between said sheet material and said platen, impression producing means cooperating with said platen ata fixed station, and an adjustably mounted shield disposed between said guiding means and said platen and adapted to be moved into and out of position between said strip and sheet material at said station but adapted to separate said strip and sheet material at al1 other points rearwardly of said station.

2. In an apparatus operating on a carbon strip, a carbon strip supply reel, a detachably mounted substantially cylindrical disposal container, means for feeding said strip from said reel to said apparatus and into said container in a substantially tangential direction, whereby said strip will become rolled up in said container without the use of a, winding spool, and means adjacent said container for severing said strip.

3. The combination with a writing machine or imprinting apparatus having a roller platen, of means for producing master sheets thereon, comprising impression producing means, means for feeding a carbon strip to said impression producing means by rotation of said platen, said strip extending partially around said platen in engagement with the surface thereof, means for guiding master sheet material around a portion of said platen, and a flexible shield supported at one edge behind said said platen and extending forwardly between said guiding means and said strip whereby rotation of said platen in a direction to feed the carbon strip will maintain said flexible shield in unwrinkled condition.

of means for producing master sheets thereon, comprising impression producing means, means for feeding a carbon strip to said impression producing means by rotation of said platen, said strip extending partially around said platen in engagement with the surface thereof, means for guiding master sheet material around a portion of said platen, and a flexible shield interposed between said guiding means and said strip.

5. The combination with a writing machine or imprinting apparatus having a roller platen, of means for producing master sheets thereon, comprising impression producing means, means for feeding a carbon strip to said impression producing means by rotation of said platen, means for feeding master sheet material to said impres'- sion producing means operable independently of said platen, and means adapted to be interposed between said carbon strip and said master sheet material at said impression producing means.

6. The combination with a writing machine or imprinting apparatus having a platen, of means for producing master sheets thereon, comprising means for guiding sheet material across said platen, means for feeding a carbon strip across said platen between said sheet 4material and said platen, impression producing means cooperating with said platen, means for advancing said sheet material along said guiding means and past said impression producing means at a rate different from that at which said carbon strip is fed by said feeding means, and adjustably mounted means overlying said guiding means for holding said carbon strip out of engagement with said sheet material at certain points and operable at will to cause said strip to make a mirror impression on said sheet material by the action of said impression producing means or to render said strip ineffective to make such impression and to prevent smudging as said sheet material is advanced relative to said carbon strip.

'7. The combination with a writing machine or imprinting apparatus having a roller platen, of means for producing master sheets thereon, comprising impression producing means, means for feeding a carbon strip to said impression producing means by rotation of said platen, distinct means for feeding sheet material to said impression producing means at a different rate than that at which said carbon strip is fed, and means operable at will to cause said strip to make a mirror impression on said sheet material by the action of said impression producing means or to render said strip ineffective to make such impression and to prevent smudging as said sheet material is advanced relative to said carbon strip.

8. The combination with a writing machine, of means for producing master sheets thereon, comprising means for feeding master sheet material and a carbon strip into cooperative relation with the impression producing means of said writing machine, said feeding means being adapted to move said master sheet material relative to said carbon strip during its feeding operations, and means for preventing smudging of said master sheet material by such relative movement, said smudge preventing means being adjustable at will to permit or to prevent the making of a mirror impression on said sheet-material from said carbon strip by said impression producing means.

9. The combination with a writing machine, of means for producing master sheets thereon. comterial and a carbon strip into cooperative relation with the impression producingmeans of said writing machine, andA means for providing engagement between said carbon strip and sheet material only in the area in which the same are in cooperative relation to said impression producing means to produce a mirror impression on said sheet material, said means being adjustable to prevent such engagement.

10. The combination with a writing machine or imprinting apparatus having a platen, of means for producing master sheets thereon, comprising means disposed behind saidl platen and extending forwardly and beneath the same for guiding sheet material across said platen, means for feeding a carbon strip across said platen between said sheet material and said platen comprising a feeding spindle, a receiving spindle and a driving connection between said spindles, and shiftable means overlying said guiding means for holding said carbon strip out of engagement with said sheet material.

11. The combination with a writing machine or imprinting apparatus having a platen, of vmeans for producing master sheets thereon, comprising means disposed behind said platen and extending forwardly and beneath the same for guiding sheet material across said platen, means for feeding a carbon strip across said platen between said sheet material and said platen comprising a feeding spindle, a receiving spindle and' means for rotat-j ing said spindles to maintain said strip tensioned, and shiftable means overlying said guiding means for holding said carbon strip out of engagement with said sheet material.

12. An attachment for a. typewriter having a platen roll for printing reversed carbon masters, comprising a roller bearing against said platen whereby a carbon strip disposed between said roller and said platen may be advanced by rotation of said platen, means for advancing a master sheet around said platen independently of the rotation of said platen, and common control means for rotating said-Jplaten and for operating said master sheet advancing means at `differential rates of speed in order to cause relative movement of said carbon strip and of said master sheet with respect to said carbon strip, said common control means including means for adjusting the rate at which said master sheet is advanced in combination with means for rotating said platen at a constant rate of speed, irrespective vof the rate of speed at which said master sheet is advanced. v

13. An attachment for a typewriter having a platen roll for printing reversed carbon masters, comprising a roller engaging the surface of said platen whereby a carbon strip disposed between said roller and said platen may be advanced by rotation of said platen, means for advancing a master sheet around said platen independently of the rotation of said platen, common control means for rotating said platen` and for operating said master sheet advancing means at dierential rates of spe-ed in order to cause relative movement of said c arbon strip and of said master sheet with respect to said carbon strip, and a flexible shield disposed around said platen and adapted to separate said carbon strip from said master sheet in order to prevent smudging of said master sheet by the relative motion thereof with respect to said carbon strip.

CHARLES A. BERGSTEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

